1. Technical Field
The present invention relates to a probe card assembly and test probes used therein. More particularly, the present invention relates to a probe card assembly and test probes therein for testing semiconductor wafers.
2. Description of Related Art
In a process for manufacturing semiconductor wafers, test equipments and probe cards are typically used for testing dies on the wafers. Some prior arts, such as U.S. Pat. Nos. 7,053,638, 6,515,358, 6,137,297, 5,670,889, 7,271,603, 7,304,488 and 6,478,596, have proposed related approaches. A probe card has precise contacting means for contacting and electrifying each die on a wafer so as to test the dies and thereby ensure that the wafer is fabricated with electrical properties and performances answering to its design specifications. In order to cater for the recently prevalent high-speed operation of semiconductor apparatuses, it is important that signal transmission between a testing machine and a probe card be free from distortion of high-frequency signals. Please refer to FIG. 1A that graphically illustrates a conventional probe card 30 having a plurality of test probes 20 and FIG. 1B that further provides an enlarged sectional view of the test probes 20 in an area A of FIG. 1A. As can be seen from these drawings, each of the test probes is independently sheltered by an insulating sleeve 21 that possesses a substantial thickness and thus even if the test probes 20 are closely arranged, an interval L1 exits between two adjacent test probes 20, thereby substantially limiting the density of arrangement of the test probes 20. In consideration of the fact that such probe card 30 currently still depends on manual operation to arrange the test probes 20 thereon and then install the insulating sleeves 21, the intervals L1 being narrow can bring difficulty to the assembling process of the probe card 30. On the other hand, the fact that resistance between the test probes 20 is in direct proportion to length of the interval L1 suggests that the thickness of the insulating sleeves 21, which contributes to the interval L1, can adversely affect signal transmission during high-frequency testing, which is critical in mass manufacture of wafers. Hence, a need exists for a structural improvement in the traditional probe card to remedy the problem of the prior arts without adding difficulty to manufacture.